1. Field of the Invention
The present invention relates to a photographic light sensitive sheet for color diffusion transfer process and, more particularly, to a silver halide photographic light sensitive sheet for the color diffusion transfer process which contains a novel dye-providing compound.
2. Description of the Prior Art
In a diffusion transfer photographic image forming process, a compound having a dye moiety bonded to a diffusibility controlling moiety is used. The diffusibility controlling moiety is a moiety which can change the diffusibility inherent in the dye-providing compound before development as a result of development under an alkaline condition. Dye-providing compounds are classified as dye releasing compounds and dye fixing compounds according to the operation of the diffusibility controlling moieties. Dye releasing compounds are non-diffusible by nature but release diffusible dyes as a result of development under an alkaline condition through the reaction of the diffusibility control moiety. As an example of such dye releasing compounds, mention may be made of dye releasing redox or DRR compounds. On the other hand, dye fixing compounds are diffusible (or release diffusible dyes) by nature, but they become non-diffusible (or do not release diffusible dyes) as a result of a development through the reaction of the diffusibility controlling moiety. As examples of such dye fixing compounds, mention may be made of compounds described in Japanese Patent Applications (OPI) 63618/'76 and 35533/'78. (The term "OPI" as used herein refers to a "published unexamined Japanese patent application".)
Color diffusion transfer color image forming processes using dye releasing redox compounds are described in Japanese Patent Applications (OPI) 33826/'73, 114424/'74, 126332/'74, 126331/'74, 115528/'75, 104343/'76; U.S. Pat. Nos. 3,928,312; 3,931,144 and 3,954,476 and Research Disclosure, vol. 130, No. 13024 (Feb. 1975). A dye releasing redox compound is a compound in which a diffusibility controlling moiety called a redox nucleus and a dye (including a dye precursor) moiety are connected. The redox nucleus renders the redox compound originally immobile by means of a ballast group attached thereto, but it splits to release a compound containing the dye moiety (dye compound) through a redox reaction under an alkaline condition. For example, a light sensitive element having a light sensitive silver halide emulsion layer associating with a redox compound of this kind is exposed to light and developed with an alkaline processing solution whereby the redox compound is oxidized in proportion to the amount of developed silver halide and splits into a compound containing a dye moiety and a nondiffusible compound (e.g., a nondiffusible quinone compound) in the presence of the alkaline processing solution. As a result, the compound containing the dye moiety diffuses into an image receiving layer to provide transferred images therein.
Examples of redox compounds which release yellow dyes are described in U.S. Pat. No. 3,928,312; Research Disclosure, supra; etc. However, the stability of their transferred images are insufficient (for example, the light fastness of the transferred image is not sufficient and the image fades to a large extent under light) and, further, transfer of the dye compounds cannot be accomplished to a satisfactory extent (e.g., the speed of transfer is too slow).
In addition, improved yellow dye releasing redox compounds are described in Japanese Patent Application (OPI) 7727/'77 corresponding to U.S. Pat. No. 4,013,633. However subsequent investigations have revealed that the dye compounds released therefrom have insufficient color fastness.
Further, Research Disclosure, vol. 164, No. 16475 (Dec., 1977) and Japanese Patent Application (OPI) 149328/'78 corresponding to U.S. Ser. No. 100,076 filed Dec. 4, 1979 describe other yellow dye releasing redox compounds, but further improvement to prevent change in hue brought about by changes in pH is needed therein.